The present invention relates to an innovative telecommunication cross connect structure based on 3D-MEMS.
Optical switching devices termed Cross Connect Switch (OXCs) for routing of optical signals in telecommunication systems are well known. The more conventional OXCs perform routing of optical signals by first converting them into electrical signals which are routed to the appropriate output port by means of electronic circuits and are then reconverted into optical signals. The switching takes place in this manner on electrical signals. With the progressive increase in transmission speeds, band widths and network complexity, conversion of signals from optical to electrical and again optical becomes ever more difficult, costly and cumbersome.
OXCs have therefore been proposed in which switching takes place directly on the optical signals employing the so-called MEMS (Micro Electro Mechanical System) members. These are virtually arrays of micro mirrors realized advantageously on silicon chips by techniques similar to those of integrated circuit production and which are controlled electrically to be oriented so as to direct the optical signals towards the appropriate output ports. It is thus possible to perform switching between a high number of ports without going through conversion of the optical signal into electrical signals. In using MEMS systems the 3D-MEMS technology appears to be the most promising.
In the more modern telecommunication networks very high data flows have to be managed and this requires highly reliable equipment. For this reason protection of the system is one of the main points which have to be faced. Another important feature is low loss of insertion in order to allow completely transparent optical switching in environments with long or very long sections. The two requirements are usually in conflict with one another. Indeed, to supply adequate protection, additional optical circuitries with associated losses and interconnections are necessary. In addition, the additional optical circuitry adds costs to the OXC architecture with MEMS.
A typical architecture comprises optical switches located on the optical cards with additional circuitry necessary for detecting optical input and output power. The main blocks of this architecture are two MEMS units with associated control electronics and various optical cards with the input-output ports and associated switches and control outlets.
A heavy optical interconnection with associated high losses and complexity is required between all the blocks.
Management of the optical fibers is then another key point in the development of OXC.
In the prior art the functions of the optical cards are partially realized even within the MEMS units to detect optical power feedback to perform fine setting of the mirrors during operation. As an alternative, more optical circuitry can be added.
However that may be, the result is always additional costs and signal losses.
The MEMS units and optical cards are often located in different racks because of the considerable space occupied by all the blocks. This causes considerable problems in management of the optical fiber arrangement.
The general purpose of the present invention is to remedy the above mentioned shortcomings by making available an innovative OCX structure with MEMS switching units which among other things should be modular, relatively low in cost, and easy to update and maintain while supplying very high performance.